Polyelectrolyte-surfactant complexes (PESCs) are important soft colloids with applications in the field of personal care, cosmetics, pharmaceutics and much else. If their phase diagrams have long been studied under pseudo-equilibrium conditions, and often inside the micellar or vesicular regions, understanding the effect of non-equilibrium conditions, applied at phase boundaries, on the structure of PESCs generates an increasing interest. In this work we cross the micelle-vesicle and micelle-fiber phase boundaries in an isocompositional surfactantpolyelectrolyte aqueous system through a continuous and rapid variation of pH. We employ two microbial glycolipid biosurfactants in the presence of polyamines, both systems being characterized by their responsiveness to pH. We show that complex coacervates (Co) are always formed in the micellar region of both glycolpids’ phase diagram and that their phase behaviour drives the PESCs stability and structure. However, for glycolipid forming single-wall vesicles, we observe an isostructural and isodimensional transition between complex coacervates and a multilamellar walls vesicle (MLWV) phase. For the fiber-forming glycolipid, on the contrary, the complex coacervate disassembles into free polyelecrolyte coexisting with the equilibrium fiber phase. Last but not least, this work also demonstrates the use of microbial glycolipid biosurfactants in the development of sustainable PESCs.<p> </p>

Amphiphiles obtained by microbial fermentation, known as biosurfactants or bioamphiphiles, are reviewed in terms of their solution experimental and theoretical self-assembly properties, interface properties and interactions with macromolecules.

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The ability to accelerate visible-light photochemical reactions in a simple setup and with little photocatalyst modification is an important challenge. We report that the adsorption of a widely used organometallic photocatalyst ([Ru­(bpy)3]­Cl2) on unmodified silica particles provides opportunities in the intensification of photochemical oxidations with an almost 10-fold increase in reactivity. This outstanding performance is attributed to noncovalent outer-sphere interactions between the substrate and the solid particles, because higher concentrations of reactive species are produced at the interface. This simple catalytic system is efficiently recycled and shows an up to 4-fold increase in stability, compared to its homogeneous counterpart. As a proof of concept, we apply this straightforward immobilization strategy to the semisynthesis of the antimalarial drug artemisinin from dihydroartemisinic acid. Our results demonstrate that the surface has a cooperative and bifunctional role, which avoids the use of hazardous acid reagents and can potentially afford a more efficient and lower cost access to this important pharmaceutical compound.